This is a Shannon Award providing partial support for the research projects that fall short of the assigned institute's funding range but are in the margin of excellence. The Shannon Award is intended to provide support to test the feasibility of the approach; develop further tests and refine research techniques; perform secondary analysis of available data sets; or conduct discrete projects that can demonstrate the PI's research capabilities or lend additional weight to an already meritorious application. The abstract below is taken from the original document submitted by the principal investigator. More than 90% of the approximately 70,000 patients resuscitated from a cardiac arrest each year suffer permanent, often severe, brain injury as a sequela to the ischemia associated with the cardiac arrest. The broad, long-term objectives of our work are to understand the damage mechanisms operative in brain ischemia and reperfusion, and thereby identify clinically effective therapeutic interventions to forestall the frequent occurrence of severe brain injury. In those brain regions most vulnerable to damage by ischemia and reperfusion, neurons exhibit a substantial inhibition of post-ischemic protein synthesis. We propose that inhibition of protein synthesis (1) occurs at the level of formation of the initiation complex, (2) as a consequence of proteolysis and oxygen radical reactions, (3) which decrease levels or alters phosphorylation of specific translation initiation factors. We further propose that (4) translation competence during reperfusion can be protected or restored by either (a) blocking proteolysis, (b) providing the active initiation factor(s) involved (in vitro) or (c) by growth factor-mediated reversal of the reperfusion- induced phosphorylation alterations of initiation factors. The specific aims of this project are to (1) examine the effect of global brain ischemia and reperfusion on the rate of initiation of protein translation, (2) examine the levels, phosphorylation state, activity, and regional localization of key translation initiation factors before and after global brain ischemia and reperfusion, (3) examine the effects of calcium overload or radical damage to cultured neurons with respect to the above parameters, (4) examine the effects of adding purified phosphorylated/dephosphorylated initiation factor(s) on in vitro protein translation in brain homogenates obtained from normal and reperfused animals and on radical-damaged or calcium overloaded cultured neurons (5) and study the effects of an exogenous growth factor on initiation factor phosphorylation and translation competence in the cell culture model and in the reperfused brain. The experimental design (1) utilizes an animal model of cardiac arrest and resuscitation to characterize the effects of global brain ischemia and reperfusion on those initiation factors that control the initiation of protein synthesis (eIF-2, eIF-2B, eIF-4E, and EIF-4 gamma), and (2) utilizes a neuronal cell culture system (derived from induced differentiation of NB104 cells) to characterize the effects of a controlled radical or calcium overload insult on these same parameters. Because the growth factor insulin has been shown to improve neurologic outcome after brain ischemia and induce stimulation of the translation system through mechanisms including dephosphorylation of initiation factors, we will also study the effects of insulin administration on translation competence and initiation factors in both model systems.